A resistive methanol sensor based on ZnO hexagonal nanorods having average diameter (60-70 nm) and average length of ∼500 nm, is reported in this paper. A low temperature chemical bath deposition technique is employed to deposit vertically aligned ZnO hexagonal nanorods using zinc acetate dihydrate and hexamethylenetetramine (HMT) precursors at 100°C on a SiO 2 substrate having Sol-Gel grown ZnO seed layer. After structural (XRD, FESEM) and electrical (Hall effect) characterizations, four types of sensors structures incorporating the effect of catalytic metal electrode (Pd-Ag) and Pd nanoparticle sensitization, are fabricated and tested for sensing methanol vapor in the temperature range of 27°C-300°C. The as deposited ZnO nanorods with PdAg catalytic contact offered appreciably high dynamic range (190-3040 ppm) at moderately lower temperature (200°C) compared to the sensors with noncatalytic electrode (Au). Surface modification of nanorods by Pd nanoparticles offered faster response and recovery with increased response magnitude for both type of electrodes, but at the cost of lower dynamic range (190-950 ppm). The possible sensing mechanism has also been discussed briefly.

We present a study of critical current density estimated through dc magnetization measurements in the superconducting alloys Ti60V40 and Ti70V30. The magnetization is irreversible below the irreversibility field (BIrr), which is different from the upper critical field for the alloys. Additionally, the alloys are found to exhibit a peak effect in magnetization below the upper critical field. The critical current densities of the alloys estimated from the magnetization results decrease strongly with increasing magnetic field. The pinning force density follows a universal scaling relation with respect to the magnetic field divided by the BIrr. The field dependence of the pinning force density is analyzed in terms of the size of the grains of the main β phase, the possible presence of dislocation arrays within the grains of the main phase, the presence of additional metallurgical phases, and the configuration of the grain boundaries in the system. The temperature dependence of critical current density is also analyzed within the framework of existing theories.

We report experimental studies of the temperature and magnetic field dependence of resistivity and dc magnetic susceptibility and the temperature dependence of zero field heat capacity in a Ti 0.6 V 0.4 alloy. The temperature dependence of the normal state dc magnetic susceptibility in this Ti 0.6 V 0.4 alloy shows T 2 lnT behavior. The temperature dependence of resistivity follows a T 2 behaviour in the range 20-50 K. On the other hand, a term T 3 lnT is needed in the expression containing the electronic and lattice heat capacities to explain the temperature dependence of heat capacity at temperatures where T 2 dependence of resistivity is observed. Such temperature dependence of dc magnetic susceptibility, resistivity and heat capacity are indications of the presence of spin-fluctuations in the system. Further experimental evidence for the spin fluctuations is obtained in the form of a negative value of T 5 term in the temperature dependence of resistivity. The influence of spin-fluctuations on the superconducting properties of Ti 0.6 V 0.4 is discussed in detail. We show from our analysis of resistivity and the susceptibility in normal and superconducting states that the spin fluctuations present in Ti 0.6 V 0.4 alloy are itinerant in nature. There is some evidence of the existence of preformed Cooper-pairs in the temperature range well above the superconducting transition temperature. Our study indicates that the interesting correlations between spin-fluctuations and superconductivity may actually be quite widespread amongst the superconducting materials, and not necessarily be confined only to certain classes of exotic compounds.Spin-fluctuations in Ti 0.6 V 0.4

Most environments favor defection over cooperation due to natural selection. Nonetheless, the emergence of cooperation is omnipresent in many biological, social, and economic systems, quite contrary to the well-celebrated Darwinian theory of evolution. Much research has been devoted to better understanding how and why cooperation persists among self-interested individuals despite their competition for limited resources. Here we go beyond a single social dilemma since individuals usually encounter various social challenges. In particular, we propose and study a mathematical model incorporating both the prisoner’s dilemma and the snowdrift game. We further extend this model by considering ecological signatures like mutation and selfless one-sided contribution of altruist free space. The nonlinear evolutionary dynamics that results from these upgrades offer a broader range of equilibrium outcomes, and it also often favors cooperation over defection. With the help of analytical and numerical calculations, our theoretical model sheds light on the mechanisms that maintain biodiversity, and it helps to explain the evolution of social order in human societies.

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